Many applications require fluid delivery systems that can dispense units of fluid having a pre-determined volume. Fluid delivery systems often use a motor speed to control the volume of fluid dispensed at one time. For example, a peristaltic fluid delivery system includes a rotating roller that squeezes flexible tubing at selected intervals, thereby pushing generally equal units of fluid along the tubing for output. The motor controls the roller's rotation speed, thereby controlling the volume of fluid dispensed as the roller squeezes the flexible tube; the faster the motor speed, the greater the volume of fluid output in a given time period.
When the system is initially installed, or when a user wishes to change the operating parameters (e.g., dispensed volume, dispensing speed, etc.), the system is calibrated to dispense the selected volume of fluid in each unit. Normally, calibration requires dispensing of a single unit of fluid, measuring the volume of the dispensed unit, and adjustment of the motor speed by, for example, manually adjusting a potentiometer controlling motor speed. These steps are repeated until the system dispenses a unit having the desired volume. Because current systems require manually iterative adjustments to obtain the desired fluid volume in each unit, calibration tends to be a tedious, labor-intensive process.
One application of such systems is a milkshake machine. A typical milkshake machine includes two separate dispensing systems. The first dispensing system dispenses a syrup component. The second dispensing system dispenses an ice cream component. The syrup component and the ice cream component have different viscosities. As such, known systems require manual, iterative adjustments during calibration to ensure accuracy in the amount of each component dispensed and throughout everyday use to maintain a desired ratio of syrup to ice cream. Similar systems are also used to dispense syrups and other liquid components used in automated coffee machines and “fountain style” soft drink dispensers. These systems also require proportional dispensing of liquid components that have different viscosities.
As such, there is a desire for a fluid delivery system and method that can reliably deliver measured units of fluid having a desired volume without requiring manual, iterative adjustments during system calibration. There is also a desire for a calibration system and method that allows calibration based on a desired dispensing time.